This invention relates in general to cooling arrangements for combustion engine systems. More specifically, this invention relates to an improved integrated engine cooling system having a single pump for supplying liquid coolant to the engine and auxiliary heat loads in an engine system, and a single heat exchanger or radiator for dissipating the heat energy generated by the engine and the auxiliary heat loads.
Cooling systems in general are well known in the art for use in absorbing and dissipating heat energy generated by a combustion engine. For example, it is well known to provide a pump to circulate a liquid coolant through internal flow passages in an internal combustion reciprocating engine for absorbing excess heat energy thrown off by the engine, and then to circulate this heated coolant to a heat exchanger such as a conventional radiator for dissipation of the absorbed heat energy. In a typical vehicular engine system, the coolant discharged from the radiator is recycled by the pump to the engine to provide the engine with a continuous flow of the liquid coolant. As a result, the engine is maintained at a selected operating temperature level according to the flow rate of the coolant and the cooling capacity of the radiator.
In many combustion engine systems, auxiliary heat loads are present which also must be maintained at a controlled operating temperature level. By way of example, in a turbocharged or supercharged engine system wherein ambient air is compressed prior to supply to the air intake of the engine, it is frequently advantageous to extract at least a portion of the heat of compression of the air prior to supply to the engine in order to further increase the air density and to reduce the overall engine heat load. To this end, a so-called charge air cooler heat exchanger is typically provided for passage of the heated compressed air in heat exchange relation with a cooling fluid, commonly a liquid coolant. In some arrangements, the liquid coolant is shared with the primary engine cooling system, and in other arrangements the liquid coolant is separate from the primary engine cooling system. In either event, the liquid coolant from the charge air cooler heat exchanger must be circulated through a cooling heat exchanger to maintain the coolant temperature within prescribed limits.
Additional sources of heat are also commonly present in many combustion engine systems. One such source of heat comprises the lubricating oil for the engine and/or turbocharger wherein the oil must be cooled to within a prescribed temperature range to prevent overheating and excess wear of mechanical components. Another common heat source comprises vaporized refrigerant within an engine driven air conditioning system wherein heat must be extracted from the refrigerant to re-condense the vapor for continuous operation of the air conditioning system. Still another commonly encountered heat load comprises the transmission fluid in a vehicular application wherein the fluid must be cooled to a prescribed temperature to prevent overheating of transmission components. In each instance, it is known to provide a heat exchanger through which a cooling fluid, such as a liquid coolant, is passed in heat exchange relation with the heat source to absorb heat therefrom. Once again, when a liquid coolant is used, it is necessary to circulate the coolant from the appropriate heat exchanger through a cooling heat exchanger to maintain the liquid coolant within prescribed temperature limits.
In the prior art, various cooling system schemes have been proposed for controlling the operating temperature levels of various heat sources or heat loads in a combustion engine system. Some of these schemes comprise separate liquid cooling circuits for each heat source, but these arrangements tend to be relatively bulky and costly in that they require a relatively large number of plumbing connections for the coolant and a relatively large number of cooling heat exchangers for dissipating collected heat energy. See, for example, U.S. Pat. Nos. 3,229,456; 3,439,657; 3,872,835; and German Publication No. 2,655,017, which disclose the use of multiple heat exchangers for dissipating heat energy from multiple heat sources in an engine system. Other systems have been proposed which attempt to integrate more than one heat source into a single liquid cooling circuit to reduce system complexity and cost. See, for example, British Pat. No. 950,020; German Pat. No. 1,140,018; and German Publication No. 2,335,248, which show a charge air cooler heat exchanger coupled in series with an engine radiator and in parallel with the engine. See also U.S. Pat. Nos. 3,162,998; 3,397,648; 3,442,258; and German Pat. No. 1,223,196, which disclose a charge air cooler heat exchanger coupled in series with both an engine radiator and the engine. However, these various prior art systems have not been totally satisfactory in tht they have not provided for close and individually selected control of the operating temperature levels of the various heat sources in the engine system. Moreover, these prior art arrangements have not been adapted for use with multiple auxiliary heat sources in the engine system, such as, for example, lubricating oil, vaporous refrigerant, and the like.
Still other systems have been proposed in the prior art in an attempt to provide temperature control of the various auxiliary heat sources in an engine system. Such other arrangements typically seek to divide flow of liquid coolant among the various heat sources in the engine system, and to provide flow control for the coolant to yield the desired operating temperatures. See, for example, U.S. Pat. No. 3,134,371. However, such arrangements tend to rely upon complex coolant flow circuitry together with multiple coolant flow mixing valves and circulation pumps to achieve the desired operating conditions.
The present invention overcomes the problems and disadvantages of the prior art by providing an improved cooling arrangement for a combustion engine system including a single heat exchanger for dissipating heat energy generated by multiple heat sources in a combustion engine system, in combination with a simplified and practical coolant flow system utilizing a single pump for circulating coolant flow to the various system heat sources for maintaining close and individual temperature control of the various heat sources.